A typical transport refrigeration unit of the type designed for mounting on the front face of a tractor trailer unit comprises a one piece, self-contained fully refrigerant charged, prewired, refrigerant/heating unit powered by a diesel engine. In such a design the evaporator fits into a rectangular opening in the upper portion of the trailer front wall. When installed, the evaporator section is located inside the trailer; and the condensing section is outside and on the front of the trailer. The condensing section consists of an engine-compressor drive package, condenser fan, condenser coil, radiator coil, control panel, relay module, refrigerant controls, piping, wiring and associated components.
Structural frame means support all of the components and facilitate attaching of the unit to the trailer front face. Also supported by the structural framework is an outer cover which includes the necessary air inlet and outlet openings for cooling, and which may be opened to provide access to the interior of the unit for maintenance and service.
Such refrigeration units preferably have a bottom panel to hide components, wiring, and the like and to improve aesthetics of the underside of the unit. Traditionally this has been provided in the form of a two piece bottom panel that was secured to the underside by way of fasteners. For the assembly of such a panel, it was necessary to have one person holding the panels in place while another person secured them to the bottom by way of fasteners.
A bottom cover should not only be simple in construction with as few parts as possible but should also be easy to assemble, be of lost cost and weight, while at the same time providing superior appearance and reliability.